EP1500878B1 - Method to terminate the operation of a vehicle heating device - Google Patents

Description

The present invention relates to a method for terminating the heating operation of a vehicle heater according to the preamble of claim 1.

Heaters, such as are used for example from auxiliary heaters or auxiliary heaters in motor vehicles, generally comprise in a combustion chamber housing a combustion chamber, in which by means of a Brennstoffzuführanordnung, so for example a metering pump or the like, liquid fuel can be fed. When constructed in the manner of a nebulizer burner, the feed takes place under pressure via a nebulizer nozzle. When constructed in the manner of an evaporator burner, the liquid fuel is generally conducted into a porous evaporator medium, further conveyed therein by capillary action, and then evaporated on the side of the porous evaporator medium facing the combustion chamber into the combustion chamber. In general, a combustion air supply arrangement, that is to say a combustion air blower, is furthermore provided, through which the combustion air required for generating the ignitable mixture can be fed into the combustion chamber. In order to be able to ignite the combustion air / fuel mixture thus produced in the case of fuel feed or evaporation and combustion air feed, a heating arrangement is also generally provided which is capable of generating elevated temperatures in a region of the combustion chamber which ignite the mixture suffice. For example, may be provided as such a heater Glühzündstift or the like. Once the combustion has started, the combustion itself is maintained by the high temperatures resulting from the combustion, so that then the operation of this heating device or a Glühzündstifts can be stopped.

In such heaters is generally in both the operating phase and when starting and ending the operation, the effort on the one hand to obtain the emitted into the environment pollutant emissions as low as possible, on the other hand to ensure that in the range of the heater itself, especially in the area the combustion chamber or the Glühzündstifts or the like, as little as possible deposits occur, which may affect the subsequent operation.

In the in the publication US 5 617 995 A disclosed shutdown takes place a first shutdown phase during a time period T ₁ . During this time, as shown for example in FIG. 11C (and analogously in FIG. 13C), the heating device ("glow plug") is in operation and remains switched on even after this switch-off phase, specifically during the time period T ₂ after the end of the first switch-off phase ,

It is the object of the present invention to provide an efficient method for stopping the heating operation of a vehicle heater.

• Erzeugen eines Abschaltbefehls,
• in einer ersten Abschaltphase nach Erzeugung des Abschaltbefehls, Zuführen von Brennstoff zu der Brennkammer,
• am Ende der ersten Abschaltphase Beenden der Brennstoffzufuhr zu der Brennkammer,
• Betreiben der Heizanordnung in der ersten Abschaltphase,
• Betreiben der Verbrennungsluftzuführanordnung in der ersten Abschaltphase.
• Beenden des Betriebs der Heizanordnung am Ende des ersten Abschaltphase.

According to the present invention, this object is achieved by a method according to claim 1 for terminating the heating operation of a vehicle heater, which vehicle heater comprises a combustion chamber, a fuel supply arrangement for supplying an adjustable. A fuel supply amount to the combustion chamber, a combustion air supply arrangement for supplying an adjustable combustion air supply amount to the combustion chamber and a heating arrangement for at least locally heating the combustion chamber, the method comprising the following measures:

• Generating a shutdown command,
• in a first shutdown phase after generation of the shutdown command, supplying fuel to the combustion chamber,
• at the end of the first shut-off phase, stop the supply of fuel to the combustion chamber,
• Operating the heater assembly in the first shutdown phase,
• Operating the Verbrennungsluftzuführanordnung in the first shutdown phase.
• Ending the operation of the heating arrangement at the end of the first shutdown phase.

It is essential in the present invention that even if the command to switch off the heater has been generated once, not immediately the fuel supply is interrupted, but continues to be fed fuel, so that the combustion can continue to be maintained, for example, with decreasing quantity and can also be ensured by the excitation of the heater occurring in this phase, that on the one hand the pollutant emissions generated in the dying combustion are minimized, at the same time also possibly in the combustion chamber depositing combustion residues in their quantity are also reduced.

The method according to the invention is carried out with high efficiency by stopping the operation of the heating arrangement at the end of the first shutdown phase.

In the phase in which the combustion is to be gradually reduced, it may be provided, for example, that in the first shut-down phase fuel is supplied at least temporarily in a fuel supply amount which substantially corresponds to a fuel supply amount of an operating phase preceding the first shut-off phase.

Furthermore, it is possible that in the first switch-off phase fuel is at least temporarily supplied in a Brennstoffzuführmenge, which is smaller than a Brennstoffzuführmenge in one of the first shutdown phase preceding operating phase. Here, for example, it can be ensured that in the first shutdown phase fuel is supplied in a minimum amount of fuel supply.

The transition to this phase, in which the combustion is to be gradually brought to a standstill, can be achieved, for example, by the fact that at the beginning of the first shutdown phase, the fuel supply amount is reduced spontaneously.

In a control technology relatively easy to implement variant can be further provided that at the beginning of the first shutdown phase, the fuel supply is reduced spontaneously. Alternatively, for a defined gradual transition to a combustion-free state, it may be provided that the fuel supply quantity in the first switch-off phase is at least temporarily reduced substantially continuously. With this variant, it can be ensured, with a continuous reduction of the fuel supply quantity, that the fuel supply quantity is reduced to zero in the first shutdown phase. Alternatively, it is of course also possible here that in the first shutdown phase, the fuel supply amount is reduced to a predetermined final fuel supply amount, wherein it may also be preferably provided that the final fuel supply amount is a minimum Brennstoffzuführmenge. If there is no transition to a state in which the fuel supply quantity is at zero due to the fuel supply continuing in the first shutdown phase, then, according to a further aspect of the invention, the fuel supply is terminated spontaneously at the end of the first shutdown phase.

Furthermore, the method according to the invention can be carried out in such a way that the quantity of combustion air supplied is reduced in the first switch-off phase. In this case, a further minimization of the pollutant emissions can be obtained by the fact that in the first shutdown phase, the Brennstoffzuführmenge and the Verbrennungsluftzuführmenge be reduced so that a substantially constant ratio of combustion air supply amount is provided to Brennstoffzuführmenge. By this measure, it can thus be ensured that the combustion also takes place in the phase in which it is to be brought to a standstill at a lambda value, which is also provided in normal operation and is optimized with regard to pollutant emissions, for example. Here, too, it may be provided that in the first shutdown phase, the combustion air supply amount substantially continuously is reduced, preferably with a constant rate reduction.

In order to ensure that even after the completion of the combustion, that possibly still remaining combustion residues or fuel residues do not lead to deposits in the combustion chamber, can further be provided that in a subsequent to the first shutdown phase second shutdown the Verbrennungsluftzuführmenge is greater than zero. Here it is possible, for example, that in the second shutdown phase, the combustion air supply is at least temporarily constant.

In another aspect, the present invention relates to a method of terminating the heating operation of a vehicle heater, which vehicle heaters include a combustor, a fuel supply assembly for supplying an adjustable amount of fuel supply to the combustion chamber, a combustion air supply assembly for supplying an adjustable combustion air supply to the combustion chamber, and a heater assembly for at least locally heating the Combustion chamber, in which method during the transition of the vehicle heater to a non-operating state phase at the same time fuel and combustion air are supplied and the heating arrangement is operated.

Fig. 1

eine prinzipielle Darstellung eines Fahrzeugheizgeräts, bei welchem das erfindungsgemäße Verfahren realisiert sein kann;

Fig. 2 bis 5

im Diagramm a) den zeitlichen Verlauf einer Brennstoffzuführmenge Abschalten eines Heizgeräts; im Diagramm b) den zeitlichen Verlauf der Erregung einer Heizeinrichtung beim Abschalten des Heizgeräts; im Diagramm c) den zeitlichen Verlauf einer Verbrennungsluftzuführmenge beim Abschalten des Heizgeräts.

The present invention will be described below with reference to the accompanying drawings. Show it:

Fig. 1

a schematic representation of a vehicle heater, in which the inventive method can be realized;

Fig. 2 to 5

in the diagram a) the time course of a Brennstoffzuführmenge switching off a heater; in the diagram b) the time course of the excitation of a heater when switching off the heater; in the diagram c) the time course of a Verbrennungsluftzuführmenge when switching off the heater.

In Fig. 1 a vehicle heater 10 is shown in principle. The heater 10 includes a combustion chamber housing 12 in which a combustion chamber 14 is formed. By means of a fuel delivery arrangement 16, for example a metering pump or the like, liquid fuel, for example gasoline or diesel, is introduced into the combustion chamber 14 via a fuel line 18. In the construction of the heater 10 in the manner of an evaporator burner, a porous evaporator medium is provided on the inner wall of the combustion chamber housing 12, in which the liquid fuel is introduced and from which this then evaporates into the combustion chamber 14. When the heater 10 is constructed as an atomizing burner, the fuel is discharged into the combustion chamber 14 via a spray nozzle as a finely atomized fuel mist.

There is also a Heizluftförderanordnung 20, for example in the form of a Heizluftgebläses provided, the drive 22 as well as the fuel delivery assembly 16 is under the control of a control unit 24.

Furthermore, a heating arrangement 26 is provided, configured, for example, as a glowing ignition pin, as a heating coil or the like, which is likewise under the control of the control unit 24.

When feeding combustion air through the Verbrennungsluftzuführanordnung 20 and fuel through the Brennstoffzuführanordnung 16 so an ignitable mixture of combustion air and fuel vapor is formed in the combustion chamber 14, which can then be ignited by operating or energizing the heating assembly 26. After the ignition and in the course of combustion, the heating arrangement 26 is generally switched off again.

In order to ensure in such a heater 10 that not only during combustion operation, but especially when stopping the combustion operation of the pollutant emissions is minimal and the risk of deposition of combustion residues in the combustion chamber 14, in particular in the area of the heating assembly 26, as well is reduced, according to the invention, a shutdown procedure is performed, which with reference to the Fig. 2 is described.

In Fig. 2 shows the diagram a) plotted over time, the fuel supply amount B, that is, for example, the per unit of time funded by the Brennstoffzuführanordnung 16 and thus directed to the combustion chamber 14 fuel volume. In this respect, therefore, this diagram a) also represents the fuel delivery capacity or fuel delivery capacity of the fuel supply arrangement 16. The diagram b) illustrates over time the status of the heating arrangement 26, in which case the status is shown either as "A", ie OFF, in a simplified manner. or "E", that is, ON. In particular, when the heating arrangement 26 can also be used for preheating the combustion chamber 14, it is of course possible to operate them in intermediate stages with medium heating power. The graph c) illustrates over time plotted the combustion air supply amount L, so for example, the volume of combustion air funded by the Verbrennungsluftzuführanordnung 20 per unit time. This diagram thus also essentially illustrates the delivery capacity or delivery capacity of the combustion air supply arrangement 20.

It is first assumed that the heater 10 is in a normal combustion operation before the time t ₀ in which a Brennstoffeinzuführmenge B ₀ is fed into the combustion chamber 14 and a Verbrennungsluftzuführmenge L _{0 is introduced} into the combustion chamber 14. Here, for example, the fuel supply B ₀ a maximum flow, ie at maximum flow rate of the fuel supply 16 subsidized amount of fuel. In this combustion phase of operation, as already stated, the heating arrangement 26 is switched off, since the temperatures required for combustion are provided by the running combustion itself.

At time t ₀ , for example, by manual input, by specifying a timer or the like in the control unit 24 generates a shutdown command or such a command to the controller 24, so that then 24 control measures are made by this controller to the heater 10 in a To transfer out of operation or shutdown. From the time t ₀ thus begins a first shutdown phase, in which first the heating assembly 26 is energized again, that is turned on, and in which is continued with the fuel supply. That is, when generating the shutdown command, the fuel supply is not terminated, but it is still fed into the combustion chamber 14 in this first shutdown phase. In the in Fig. 2 In the example illustrated in FIG. 1, it can be seen that the fuel supply amount B also delivered in the preceding operation phase is further fed into the combustion chamber 14. The combustion air supply assembly is controlled by the controller 24 such that the amount of combustion air supplied into the combustion chamber 14 gradually decreases from the amount L _{0 delivered} in the preceding phase of operation, for example, decreases at a constant rate.

At the end of this first shutdown phase, ie at time t ₁ , the fuel supply is terminated spontaneously, so that at this time t _1, for example, by spontaneous termination of the operation of the Brennstoffzuführanordnung 16 or by appropriately driving a shut-off valve, the fuel supply B drops to zero. Simultaneously with the termination the fuel supply at the end of this first shutdown phase and the excitation of the heating assembly 26 is terminated, so that it goes back to the off state at time t ₁ . The combustion air supply amount L has already dropped significantly, but still has a non-zero value at the end of this first shutdown phase.

In a subsequent to the time t ₁ second shutdown phase, the combustion air supply amount L is first further reduced until it assumes a minimum value L _min and is then held at a minimum time t ₂ at this time. At time t ₂ , the second shut-off phase and thus the entire shut-off process is then completed, at which time the operation of the combustion air supply arrangement 20 is terminated, so that the combustion air supply amount L decreases to zero.

By the procedure described above, in which during a first shutdown phase further fuel is introduced into the combustion chamber 14 and at the same time the heating assembly 26, so for example a Glühzündstift is energized, it is ensured that, in particular in the region of this heating arrangement 26, the occurrence of deposits is prevented. This contributes in particular to the continued continued also by energizing the heating assembly 26 induced combustion. Furthermore, the continued operation of the Verbrennungsluftzuführanordnung 20 even after the termination of the first shutdown, ie after the end of the fuel supply ensures that still in the combustion chamber 14 existing fuel residues or combustion product residues are conveyed out of the combustion chamber 14 and can not abdgern there. Thus, with reduced pollutant emissions in the shutdown this shutdown procedure according to the invention ensures by preventing deposits for an increased life of the entire heater 10th

An alternative procedure is in Fig. 3 illustrated. One recognizes in Fig. 3 in that fuel is still supplied in the first switch-off phase, that is to say between the times t ₀ and t ₁ , but that the fuel feed amount B is set to a value B _min which is lower than the fuel feed amount B ₀ present in the preceding heating operation, which for example is the minimum fuel feed rate the fuel supply assembly 16 may correspond. At the end of the first shut-off phase, ie at the time t ₁ , the fuel supply is then also terminated in this procedure, simultaneously with the termination of the operation of the heating assembly 26. By the continuous supply of combustion air in the second shutdown phase, ie until the time t ₂ , can here also be taken to ensure that combustion residues or fuel residues are flushed out of the combustion chamber 14.

It should be noted that, of course, the reduction of the Brennstoffzuführmenge in the first shutdown phase or at the beginning of the same can also be done in several steps, so that there is a multi-stage transition. It should also be pointed out that, of course, in the previously described embodiment variants of the procedure according to the invention, as in the embodiment variants to be described below, the excitation of the heating arrangement 26 can be tuned to the first shutdown phase, ie can begin at the beginning of the first shutdown phase and at the end of the first shutdown phase Abschaltphase can be stopped again, as shown in the figures. Of course, it is also possible to start the Errgeung for example, before reducing the Brennstoffzuführmenge B, so that, for example, after the shutdown command, the heating assembly 26 is turned on immediately, the reduction of the fuel supply B occurs only delayed. Even at the end of the first shutdown phase energizing the heating assembly 26 may occur before the complete termination of the fuel supply or preferably only afterwards. As a result, when stopping the fuel supply, However, even further energized heating assembly 26 remaining fuel residues can be safely burned by the provided in the heating assembly 26 and the combustion chamber 14 high temperatures. Furthermore, it is of course also possible that the combustion air supply quantity L is already reduced to the value L _min in the first switch-off phase and then a substantially constant amount of combustion air supply L is provided in the entire second switch-off phase, ie until the combustion air supply is completely shut off.

Another alternative procedure according to the invention is in Fig. 4 shown. It can be seen here that in the first switch-off phase the fuel supply quantity B is not reduced spontaneously or stepwise but continuously, preferably at a constant rate of decrease, until, for example, at the end of the first switch-off phase, ie at time t ₁ , a minimum fuel supply amount B _{min is} reached. At time t ₁ , the fuel supply is then set again spontaneously. It should also be noted here that the decrease of the fuel supply B can also be done so that can be passed before the time t ₁ in a state of constant Brennstoffzuführmenge, so that the continuous ramp-like decrease in Brennstoffzuführmenge only during a certain period of the first shutdown occurs, for example, at the end, while fuel is still supplied at a constant rate in advance. By the in Fig. 4 The procedure shown ensures that the reduction of the fuel supply amount B is better matched to the reduction of the combustion air supply amount L. As a result, the ratio of combustion air supply amount L to fuel supply amount B remains closer to a ratio intended for normal operation, which is also optimized in terms of pollutant minimization. In Fig. 5 a variant is shown in which during the entire first shutdown phase, ie between the times t ₀ and t _1, this ratio L / B remains substantially constant, so that when the fuel supply amount B is zero at the end of the first shut-down phase, and the combustion air supply amount L is also zero.

Again, it should be noted that, of course, only in one or more sections of the first shutdown phase, the continuous decrease in the fuel supply B and correspondingly a continuous decrease in the Verbrennungsluftzuführmenge L can be provided while working in other periods, for example, with constant fuel supply B and correspondingly constant combustion air supply amount L. becomes. Furthermore, it is particularly in the in Fig. 5 illustrated variant of the procedure according to the invention also possible that after the first shutdown, ie after completion of the fuel supply, the Verbrennungsluftzuführanordnung 20 is activated again to ensure that in the combustion chamber 14 still existing combustion residues or fuel residues are reliably flushed out.

The procedures according to the invention when switching off a heater 10 provided in a vehicle thus provide for improved operation, in particular also a prolonged service life of the heater 10, through reduced pollutant emissions and, in particular, reduced combustion residue deposition in the region of the combustion chamber 14. Of importance is the fundamental principle of the present invention that at the transition to the off state for a given phase at the same time still fuel and combustion air are supplied, while the heating arrangement is energized to provide for a still ongoing, but gradually decreasing combustion.

Claims (18)

1. A method for terminating the heating operation of a vehicle heating device (10), the vehicle heating device (10) comprising a combustion chamber (14), a fuel supply arrangement (16) for inserting an adjustable fuel supply quantity into said combustion chamber (14), a combustion air supply arrangement (20) for inserting an adjustable combustion air supply quantity into said combustion chamber (14) as well as a heating arrangement (26) for heating at least locally said combustion chamber (14), the method comprising the following measures:

   - generating a switch-off command,

   - in a first switch-off phase after generating said switch-off command, inserting fuel into said combustion chamber (14),

   - at the end of said first switch-off phase stopping the fuel supply towards said combustion chamber (14),

   - operating said heating arrangement (26) in said first switch-off phase,

   - operating said combustion air supply arrangement (20) in the first switch-off phase,

   characterized by the operation of said heating arrangement (26) being stopped at the end of said first switch-off phase.
2. The method according to claim 1,
   characterized in that in said first switch-off phase fuei is inserted at least temporarily in a fuel supply quantity (B) corresponding substantially to a fuel supply quantity (B₀) of an operating phase preceding the first switch-off phase.
3. The method according to claim 1 or 2,
   characterized in that in the first switch-off phase fuel is inserted at least temporarily in a fuel supply quantity (B) which is smaller than the fuel supply quantity (B₀) of an operating phase preceding the first switch-off phase.
4. The method according to claim 3,
   characterized in that in the first switch-off phase fuel is inserted in a minimum fuel supply quantity (B_min).
5. The method according to claim 3 or 4,
   characterized in that in the beginning of said first switch-off phase said fuel supply quantity (B) is reduced spontaneously.
6. The method according to one of claims 2 to 5,
   characterized in that in the first switch-off phase fuel is supplied in a substantially constant fuel supply quantity (B).
7. The method according to one of claims 1 to 6,
   characterized in that in said first switch-off phase said fuel supply quantity (B) is at least temporarily reduced in a substantially continuous manner.
8. The method according to claim 7,
   characterized in that said fuel supply quantity (B) is reduced with a substantially constant rate.
9. The method according to claim 7 or 8,
   characterized in that in the first switch-off phase said fuel supply quantity (B) is reduced to zero.
10. The method according to claim 7 or 8,
    characterized in that in the first switch-off phase said fuel supply quantity (B) is reduced to a predetermined final fuel supply quantity.
11. The method according to claim 10,
    characterized in that said final fuel supply quantity is a minimum fuel supply quantity (B_min).
12. The method according to one of claims 1 to 11,
    characterized in that at the end of the first switch-off phase the fuel supply is stopped spontaneously.
13. The method according to one of the preceding claims,
    characterized in that in the first switch-off phase said combustion air supply quantity (L) is reduced.
14. The method according to claim 13,
    characterized in that in the first switch-off phase said fuel supply quantity and said combustion air supply quantity (L) are reduced so that a substantially constant ratio of combustion air supply quantity (L) and fuel supply quantity (B) is provided.
15. The method according to claim 13 or 14,
    characterized in that in the first switch-off phase said combustion air supply quantity (L) is reduced substantially continuously.
16. The method according to claim 15,
    characterized in that said combustion air supply quantity (L) is reduced at a substantially constant rate.
17. The method according to one of claims 13 to 16,
    characterized in that in a second switch-off phase succeeding the first switch-off phase the combustion air supply quantity (L) is greater than zero.
18. The method according to claim 17,
    characterized in that in the second switch-off phase said combustion air supply quantity (L) is at least temporarily constant.

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